International mediators are in an eleventh-hour scramble to find delegates willing to attend Darfur peace talks on Saturday after a string of boycott announcements by rebel movements.

Diplomats from the UN and the African Union are scouring relief camps in Darfur and Chad, looking for tribal elders, refugee leaders and the heads of women's groups, in an attempt to salvage the negotiations in Sirte, Libya, according to officials familiar with the efforts.

The UN is also facing serious problems deploying a hybrid UN-AU peacekeeping force authorised in July by a UN resolution. Deployment is being blocked by the Sudanese government - which objects to the inclusion of non-Africans - and by a lack of essential equipment including helicopters and transport aircraft.

Jordan had promised to contribute attack helicopters but they were recently discovered not to be of the required standards, and the UN secretary general has made urgent appeals to South Africa, China and a handful of other countries to provide the aircraft. Meanwhile, Sudan's generals have blocked the inclusion in the force of Thai and Nepalese battalions, apparently suspecting that they would be too western-oriented.

"The UN is facing the prospect of an absolute disaster here," an African Union adviser said.

The rush to find delegates is in part a late attempt to diversify a Darfur delegation that is dominated by the leaders of small armed militias. "There is a realisation that even if the rebel movements came to Libya in their entirety, they are probably not very representative," said Lawrence Rossin, a retired US ambassador who now works for a human rights group, the Save Darfur Coalition.

It now seems likely, however, that the main rebel movements will not turn up. Abdul Wahid al-Nur, the leader of the Sudan Liberation Movement, has resisted pressure to attend from British, French and Dutch diplomats. He wants the peacekeeping force in place before talks start.

Another major rebel group, the Justice and Equality Movement, has said it will boycott the talks, after abortive efforts in the southern Sudanese town of Juba to find a common Darfur position in the talks with the Khartoum government.

On Tuesday, the leader of an SLM splinter group, Ahmed Abdul Shafi, added his name to the list of non-attendees, saying the atmosphere was not "conducive" to success.